1. Field of the Invention
The present invention relates to lowering power consumption of a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display.
2. Description of the Prior Art
In general, a portable pressure measuring apparatus used as an altimeter comprises at least a semiconductor pressure sensor for sampling and measuring a pressure at regular intervals, an operation control section for calculating an altitude by using a known pressure-altitude conversion formula, a display section for displaying the altitude, and a battery for supplying power to these components.
In the Japanese Utility Model Publication No. 5-11455, there is disclosed a portable pressure measuring apparatus which can be used in both a bathometer and an altimeter, comprising at least a semiconductor pressure sensor, a control section, and a display section, wherein a sampling period for a pressure measurement can be switched to suppress power consumption of the semiconductor pressure sensor. More specifically, a sampling measurement is performed for a pressure measurement only for a certain period of time in the 1-second period at measuring the water depth, while a sampling measurement is performed in the 1-second period immediately after starting an altitude measurement and afterward in the 1-minute period at measuring the altitude; in case of a significant altitude change, the sampling measurement is performed in the 1-second period for a certain period of time for each so as to lower the power consumption.
In this conventional portable pressure measuring apparatus, the water depth measurement and the altitude measurement are manually switched to each other by key inputs. In addition, it is determined automatically by the control section whether the altitude change is significant. More specifically, the control section compares the latest altitude data with altitude data obtained one minute before and determines the altitude change to be significant if the difference between them exceeds a threshold.
In short, after an elapse of a certain time period after starting the altitude measurement, the conventional portable pressure measuring apparatus measures a pressure in the 1-minute sampling period unless the altitude change is significant or in the 1-second sampling period if the altitude change is significant and these sampling periods are automatically switched to each other with measuring the rate of altitude change per minute, thereby concurrently achieving a real-time altitude display and low power consumption.
The conventional portable pressure measuring apparatus, however, has only two kinds of carriage sampling periods such as 1-minute and 1-second periods, and therefore they cannot be optimum carriage sampling periods for use in skydiving, skiing, mountain climbing, and the like. In this connection, normal carriage sampling periods for skydiving, skiing, and mountain climbing are 100 milliseconds, 100 milliseconds to 1 second, and 1 minute, respectively, for the portable pressure measuring apparatus. Therefore, the conventional portable pressure measuring apparatus has a problem that it is still unsatisfactory for Concurrently achieving the low power consumption and the real-time altitude display.
Furthermore, in the conventional portable pressure measuring apparatus, a user manually performs switching operations between the water depth measurement and the altitude measurement by means of key inputs and the user manually terminates the measurement by key inputs after the use of the apparatus though it is not specifically indicated. Therefore, the user may forget to make a key input for terminating the measurement; if so, the measurement mode continues, thereby causing a problem of wasteful power consumption.
To solve these problems, the present invention is provided. It is an object of the present invention to provide a portable pressure measuring apparatus to be used as an altimeter, which can be automatically switched to an optimum sampling period in accordance with a use of the apparatus before a pressure measurement at all times.
Taking into consideration that a portable pressure measuring apparatus is used for various uses, sampling periods coping with various rates of altitude change are preset so that the current sampling period is automatically switched to another whenever the rate of altitude change exceeds a threshold so as to perform a pressure measurement in the optimum sampling period. Furthermore, to prevent the portable pressure measuring apparatus from consuming wasteful power during no movement, the pressure is not measured at all or is measured in a very long sampling period during no movement.
More specifically, according to an aspect, the present invention which achieves the above object relates to a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display, comprising movement detection means, wherein a pressure is measured in a first (or movement) sampling period suitable for real-time display if the movement detection means detects a movement and the pressure is not measured when the movement detection means detects no movement.
According to another aspect, the present invention which achieves the above object relates to a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display, comprising movement detection means, wherein a pressure is measured in a first (or movement) sampling period suitable for the real-time display if the movement detection means detects a movement or in a second (or non-movement) sampling period which is longer than the movement sampling period when the movement detection means does not detect any movement.
According to still another aspect, the present invention which achieves the above problem relates to a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display, comprising rate of altitude change operation means and means for setting Nxe2x88x921 thresholds from the maximum threshold to the minimum threshold, wherein a pressure is measured in the Nth sampling period which is the minimum period if the rate of altitude change is equal to or greater than the maximum threshold, in the 1st sampling period which is the maximum period if the rate of altitude change is smaller than the minimum threshold, or in a sampling period having a length corresponding to respective thresholds if the rate of altitude change is between the maximum threshold and the minimum threshold. Then there is disclosed an embodiment in which the above N is assumed to be 3.
According to still another aspect, the present invention which achieves the above problem relates to a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display, comprising movement detection means, rate of altitude change operation means, and means for setting Nxe2x88x921 thresholds from the maximum threshold to the minimum threshold, wherein, if the movement detection means detects a movement, a pressure is measured in the Nth sampling period which is the minimum period if the rate of altitude change is equal to or greater than the maximum threshold, in the 1st sampling period which is the maximum period if the rate of altitude change is smaller than the minimum threshold, or in a sampling period having a length corresponding to respective thresholds if the rate of altitude change is between the maximum threshold and the minimum threshold and wherein, unless the movement detection means detects any movement, a pressure sampling measurement is not performed. Then there is disclosed an embodiment in which the above N is assumed to be 2.
Furthermore, according to another aspect, the present invention which achieves the above problem relates to a portable pressure measuring apparatus for a pressure sampling measurement and a real-time altitude display, comprising movement detection means, rate of altitude change operation means, and means for setting Nxe2x88x921 thresholds from the maximum threshold to the minimum threshold, wherein, if the movement detection means detects a movement, a pressure is measured in the Nth sampling period which is the minimum period if the rate of altitude change is equal to or greater than the maximum threshold, in the 1st sampling period which is the maximum period if the rate of altitude change is smaller than the minimum threshold, or in a sampling period having a length corresponding to respective thresholds if the rate of altitude change is between the maximum threshold and the minimum threshold and wherein, unless the movement detection means detects any movement, a pressure is measured in the non-movement sampling period longer than the maximum period. Then there is disclosed an embodiment in which the above N is assumed to be 2.